1. The Field of the Invention
The present invention relates to a driving device, which moves forward and backward in parallel with a setting surface for use in production facilities of various production fields, a transfer facility in a transportation field, a care facility in a medical welfare field, a stage facility in an art field and the like. More specifically, the present invention relates to an engagement chain type driving device, which uses an engagement chain as a driving medium for moving forward and backward.
2. The Relevant Technology
One example of a driving device used for hoisting and lowering heavy articles is a so called chuck chain, which uses a pair of engagement chains, which are integrally hoisted and lowered while engaged with each other. FIG. 11 illustrates an example of an engagement chain 550 which is used as the conventional driving device. Various chains have been developed with hook surfaces 555b of a variety of shapes formed in respective link plates 555, different pitches between pins, a variety of pitches between bushes and the like. In one example, a buckling limiting flat surface 555a is formed at an opposite side region of the hook surface in a longitudinal direction of the plate, where the flat surface is used to hold the chain engagement position. As shown in FIG. 11, plate shapes are typically formed so that some space is produced between the buckling limiting flat surfaces 555a which face each other when a pair of engagement chains 550 are engaged with each other.
However, in the conventional driving device a backlash is generated between link plates 555a due to spaces being generated between the bucking limiting flat surfaces 551, meaning that the rigidity of a pair of engagement chains 550 engaged with each other cannot be ensured. Therefore, it is necessary to provide an auxiliary guide means 590, which prevents buckling and inclination in the engagement chains 550 so as to guide a stable hoisting/lowering drive for a load supporting member 510. For example, an auxiliary means 590 composed of a pantograph mechanism is shown in FIG. 12 between the load supporting member 510 and a setting floor surface side. One problem with this structure, however, is that the entire device becomes complicated, and the flexibility of designing of the device is lost.
In addition, the reduction in the buckling strength in a pair of engagement chains 550 due to the space generated between the buckling limiting flat surfaces 555a makes it difficult to support large weights using a vertical wall surface or ceiling surface. Thus, various systems were developed where a load supporting member 510 using the pair of engagement chains 550 in a floor setting form, as described in the Japanese Patent Publication No. 3370928. As previously mentioned, however, when the engagement chain 550 is used in a driving device in a suspended form using a ceiling surface as a setting surface or a driving device in a cantilever supporting form using a vertical wall surface as a setting surface, problems with the reduced buckling strength in the engagement chains 550 has become significant.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced